A man walks on a pedestrian overpass on a hazy day in Beijing’s central business district in this 2010 file picture. (AP Photo/Alexander F. Yuan)

(CNSNews.com) – The State Department disputes China’s assertion that the monitoring and reporting of air quality by the U.S. Embassy in Beijing violates international treaties governing diplomatic and consular relations between countries.

“I’m not an expert in Vienna Conventions, but I’m pretty sure that this is no violation of the Vienna Convention,” department spokesman Mark Toner told a briefing Tuesday.

The embassy reports on the quality of air in the Chinese capital, Toner said, to enable American citizens there “to make better daily decisions regarding the safety of outdoor activities.” The U.S. consulate general in Shanghai and consulates in other Chinese cities also publish air quality readings.

Toner noted that a similar daily service exists in many American cities, adding that “air pollution, quite frankly, is a problem in many cities and regions in China.”

On Tuesday, China’s vice minister of environmental protection, Wu Xiaoqing, told a press conference that the monitoring and reporting on air quality data by foreign missions was encroaching on the “government’s privilege.”

Diplomats were obliged to respect and abide by the laws and regulations of host countries and not interfere in their domestic affairs, Wu said, citing the Vienna Conventions on diplomatic and consular relations.

He urged embassies and consulates to stop publishing the data, saying it was not “representative.”

China’s ire appears to relate less to the actual readings reported by the U.S. Embassy – which provides them daily via Twitter and on its Web site – than it does to accompanying assessments. A reading taken at 11 AM local time on Wednesday, for instance, declared Beijing air quality to be “Very Unhealthy (at 24-hour exposure at this level).”

The Chinese government also measures air quality, and Wu conceded Tuesday that its official readings in Beijing and Shanghai “are pretty close to the daily average released by some embassies and consulates.”

However, he added, “assessments are drastically different as they use their standards to evaluate China’s air quality, which is unscientific.”

China has far less stringent air pollution regulations than the United States.

“It’s okay for a foreign embassy to publish some data but I don’t think it’s right to make their own assessment, as their data can’t reflect the city’s air quality as a whole,” Pan Xiaochuan, a professor at Peking University’s School of Public Health, told the Communist Party-affiliated Global Times.

“China and the U.S. have different cultural and economic backgrounds, and we shouldn’t be led by their values and standards.”

On its Web site, the embassy makes clear that the readings taken from its single machine cannot provide citywide analysis.

The dispute is centered on so-called PM2.5 data.

PM stands for “particulate matter” – solid particles and liquid droplets found in the air in varying sizes.

According to the U.S. Environmental Protection Agency, particles smaller than 10 micrometers in diameter (PM10) are of concern as they can be inhaled. Those finer than 2.5 micrometers in diameter (PM2.5) “are believed to pose the largest health risks,” says the EPA.

“Because of their small size (less than one-seventh the average width of a human hair), fine particles can lodge deeply into the lungs.”

A Global Times commentary published Wednesday said Wu’s request for foreign embassies to stop reporting air quality data was “valid.”

“Whether the U.S. embassy’s monitoring is based on its own interests or concern for China’s public affairs, it is unprecedented for the public’s attention and attitude on air quality to be shaped by incomplete information published by diplomats,” it said.

The commentary noted that Chinese Internet users accessing the embassy’s reports appeared to ascribe greater credibility to the U.S. information than to the official Chinese data.

“Why do the incomplete figures from the U.S. embassy receive more support than the official data?” it asked. “It will take strenuous efforts to win back official credibility.”